Concave bottom boat hull



March 27, 1951 swEE-NY ETAL 2,546,704

CONCAVE BOTTOM BOAT HULL- Filed May 16, 1946 INVENTORJ- v BY Patented Mar. 27, 1951 UNITED 2,546,704 ooNoAvE BorroM BOAT HULL Robert D. Sweeny and Wencel L. Coutchure, To-

ledo, Ohio, assignors to Wm. H. Cock, Toledo,

Ohio, trustee Application May 16, 1946, Serial No. 670,161

1 Claim.

This invention relates to efficient configuration of the submersible region of watercraft for current or propulsion advantage in craft movement relatively to its water support.

This invention has utility when incorporated in boat bottoms, especially for speed boats and watersled types, wherein the relative movement, between the boat bottom and its water support, directs the supporting water body in a converging course to a throat for expulsion spill therefrom in Venturi-simulating performance.

Referring to the drawings:

Fig. l is a side elevation of an embodiment of the invention in the bilaterally symmetrical hull of a speed boat type of watercraft;

Fig. 2 is a partial bottom plan view of the craft of Fig. 1;

Fig. 3 is a fragmentary view, on an enlarged scale, looking at the forward end or prow of the craft of Fig. 1; and

Fig. 4 is a view of the stern or rear elevation of the craft of Fig. 1, on an enlarged scale, with a portion broken away.

In the craft of this disclosure, there is shown a prow I from which there is a downwardly extending receding convex portion 2 flaring to a but slightly concave nearly flat transverse bottom portion 3. Aft therefrom is fairing downward portion 4 medially having a deepening trough portion 5. The portion 4 as the tapering or converging sides for the trough 5, are in course for defining directly aft a medial straight line from the prow rib l, 2. This line defines the top side of a throat 8 from which there is a flare or widening spill 1, more pronounced, say by four or five times in extent linearly of the craft, than the fairing converging region :5 as bilaterally symmetrical for the bottom. Forwardly of the intake for the throat 6, the region 4 has therefrom a nearly flat aft portion 8 centrally but slightly upward from a stern lower edge 9 as to its junction 10 with riser corner I I of a stern l2.

The stern l2 has its lower portion more abrupt in its rise away from the water to a rounded portion [3 into a deck or top portion i l. The top M has a junction line I5 with the opposite sides It of the craft. The sides 5 -5 from the lower rear corner It} extend forwardly in forming corner or edge H as the bounds for the portions 8, l, and as marginally rising to cross the horizontal direction determined by the prow receding portion 2 in lineal register with the root of the trough 5 and the central deeper portion of the throat 5 and spill l therefrom, establish a water relative flow direction for the craft to ride. The rise of this corner ill is by line H8 in passing the approximately flat region 3 forward of the center of the craft bottom, with the upward pitch of this line it bowing inwardly to a junction with the prow as much upward as two-thirds the craft major height in the hull portion shown. The straight side edges or corners ii in their extent forwardly from the stern [2, are in a plane downwardly offset the depth of the boat bottom concavity or countersink in parallelism to the medial line of the boat bottom. It is thus seen that forward portions 19 of the boat sides 16 have a slight outward flare upward in entering oncoming water,

with sufficient central prow projection to contribute to steering control. Therebelow, more receding bottom,portions 20 extend to the region 3.

In riding the waves, the prow l definitely establishes the direction for relative movement. The volume of the water displaced has a very high, if not actual major portion thereof, not spread to establish a wake, but for the craft to ride thereover in the water flow relatively thereto. In this transit of the boat bottom, there seems to be in effect a gathering action for the water volume to be directed by the portions 2!! to pass over the region 3 for the volume to be retained as the fairing-depth increases rearwardly. The stream velocity build-up reaches its maximum at the throat 6. Then with its relatively sudden release by the outcurved region I, there is a resulting propulsive kick, of important boat transit value. There is accordingly achieved in this bottom boat configuration, a Venturi-like thrust upon the stern of the craft. It is thus found that there is relatively a less net resistance in the boat movement relatively to the water in which it is supported. The weight of the boat has sufiicient confining action to hold the flow to Venturi performance, notwithstanding there be rigid Venturi walls only upward.

In order fully to comprehend the advance achieved by the sub-boat flow control as herein disclosed, it is in order to consider comparison a similar over-all dimension craft of like displacement. The otherwise-than-as-to-the-bottom identical craft, in a test procedure, with the embodiment herein, were moored or tethered in similar flow stream. As light or empty, for each thereof, the Venturi-like bottom craft of the invention herein disclosed only half the pull on the tether line to that of the ordinary speed boat nearly flat bottom craft. A stern load on the Venturi-like bottom craft, sufiicient to double the tether line pull therefor, developed a like increase for the non-Venturi-like bottom craft, leaving a one-third advantage still for the design herein.

Considering the initial tether pull for the Venturi-like bottom boat as unity, the first aft load as 2, then a third loading with the second aft load to bring the tether pull up to 2 /2, doubled the pull shown by the non-Venturi-like bottom boat, or had its tether pull up to 6. With the same load, but not all aft, but distributed aft and forward for a more balanced condition, and the device of this invention still shows 2 /2 pull on the tether, while for the non-Venturi-like boat it decreased its tether pull from 6 to 4, with still the advantage for the invention of 1 Relocation of this last load, local amidship, does not disturb the 2 for the structure of the invention, while it boosted that of the non-Venturi-like bottom from i to 5twice the advantage for the invention type boat. From the foregoing, it is apparent that load shifting or various placings for the load seem to have an undisturbed or con stant advantage under the invention boat.

Additional tests were made at 40 cross-stream tethering of the two craft, each with the final load above amidship. This developed an increase in the tether pull for the boat of the invention from 2 /2 to 3, While for the non-invention craft its tether pull remained undisturbed and still at 6, that is, as originally loaded aft and over the midship loading therefor of 5.

What is claimed and it is desired to secure by Letters Patent is:

A bilaterally symmetrical boat hull comprising a bottom, a pair of ides, a stern and a prow,

said hull being provided with side edges at the bottom lying in a plane from the stern, said edges then rising and bowing inwardly to form a junction centrally of the prow, the prow having a convex downward extent past said junction and to a medial straight line for the bottom extend-- ing to the stern in approximate parallelism with said plane, the hull bottom from the prow flaring outwardly to the bowing portion of the side edges with the bottom flaring to approach a transverse straight iine to intersect the medial line, the bottom then in extent aft being of concavity increasing to the plane, with the concavity of the bottom then narrowing to form a medial throat spaced an abrupt flare from the stern.

ROBERT D. SWEENY. WENCEL L. COUTCHURE.

REFERENCES QITED The following references are of record in the file of this patent:

UNITED SIATES PATENTS Number Name Date 128,437 MacPherson June 25, 1872 597,195 Evesson Jan. 11, 1898 911,806 Broward Feb. 9, 1909 1,613,953 Hunter Nov. 28, 1911 1,942,636 Apel Oct. 29, 1912 1,886,507 Wehr Nov. 8, 1932 1,898,876 Heljesson Feb. 21, 1933 FOREIGN PATENTS Number Country Date 2,093 Great Britain Dec. 2, 1899 213,390 Switzerland -1 Mar. 16, 1941 

